Typically, panoramic photos are divided into ring panorama and full panorama, and the difference thereof lies in that the ring panorama does not include the place on the top of the head or beneath the foot, while the full panorama includes the panorama in the visual field on the top of the head and even beneath the foot. Due to the existence of a bracket, most underneath visual fields are generated during post production. The vast majority of panoramic photos are spliced by photos in different directions, and the principle that the position of a lens node is unchanged during photo shooting should be abided by. This operation of maintaining the lens node unchanged mainly depends on a panoramic head.
Most existing panoramic heads are universal to a certain extent, and users can select shooting devices within a certain range, thereby having a certain flexibility. However, each user usually uses only one of the shooting devices, therefore such flexibility is not meaningful for ordinary users, but it brings a lot of troubles and problems:
1. The user needs to find out the node of the used lens. The node of the lens is a point on a certain position on a centre shaft of the lens, and the coordinates of the point in the space can represent viewpoint coordinates when the lens is used for shooting. However, the positions of the nodes of different lenses are different and cannot be marked on the lenses. The user needs to determine the position of the node of the lens by a measurement experiment in advance, and in the experimental method, the distance between the lens and a rotating shaft is adjusted, and the relative position relationship between scenes of different distances before and after the adjustment is observed to gradually measure the approximate position of the node of the lens. Due to the experience of a surveyor and other factors, the measurement accuracy may be quite low.
2. When mounting the shooting device, the user needs to align the lens node to the rotating shaft. Most existing panoramic heads have two slide rails and more than two locking devices to adapt to the sizes of different shooting devices, such that the process of only mounting the shooting device during shooting is very troublesome. In addition, these adjustable slide rails and locking devices will bring errors, resulting in that the mounted lens node is not located at a correct position actually, such that the lens node generates displacement during shooting.
3. A combination structure of a rotating shaft and a cantilever generally exists on most existing panoramic heads. This structure is an upward visual angle for keeping the lens node unchanged, the cantilever structure is easy to deform, thereby causing an error, and the deformation will increase over time.
4. The user usually determines the range of the visual field according to the focal length of the used lens and the photo size of the shooting device, and then the number of the photos necessary for synthesizing a panoramic photo is calculated.
5. The existing panoramic head has a larger size and weight, thereby being not convenient to carry. Moreover, it is difficult to dispose in a small plane or space (e.g., on a desktop, inside a car); and because of the complex structure, the manufacturing cost of the existing panoramic head is higher.
In short, the existing panoramic head has the shortcomings of troublesome operation, error proneness, low measurement accuracy, complex structure and high cost.